Investments in Unconsolidated Subsidiaries - Schedule of Condensed Financial Information of Equity Method Investments (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Assets	$ 14,488,728	$ 15,270,870
Liabilities	6,153,231	6,491,549
Non-controlling interests	(7)	(183)
Revenue	1,099,674	1,106,076	1,093,792
Operating income (loss)	(212,867)	(82,604)	(76,739)
Net (loss) income	(234,206)	131,910	126,639
Global Investment Management [Member]
Schedule of Equity Method Investments [Line Items]
Current assets	1,577,549	1,148,658
Non-current assets	10,989,168	12,546,920
Assets	12,566,717	13,695,578
Current liabilities	1,372,002	1,034,040
Non-current liabilities	3,971,690	4,705,551
Liabilities	5,343,692	5,739,591
Revenue	894,725	874,875	833,343
Operating income (loss)	(307,133)	(241,829)	(161,966)
Net (loss) income	(320,206)	(26,075)	64,696
Development Services [Member]
Schedule of Equity Method Investments [Line Items]
Real estate	1,692,769	1,372,379
Other assets	130,469	109,328
Assets	1,823,238	1,481,707
Notes payable on real estate	539,186	569,023
Other liabilities	220,864	134,809
Liabilities	760,050	703,832
Revenue	39,753	70,343	97,084
Operating income (loss)	63,181	130,873	63,472
Net (loss) income	54,468	129,563	38,720
Other [Member]
Schedule of Equity Method Investments [Line Items]
Current assets	69,010	56,359
Non-current assets	29,763	37,226
Assets	98,773	93,585
Current liabilities	35,414	33,791
Non-current liabilities	14,075	14,335
Liabilities	49,489	48,126
Non-controlling interests	(7)	(183)
Revenue	165,196	160,858	163,365
Operating income (loss)	31,085	28,352	21,755
Net (loss) income	$ 31,532	$ 28,422	$ 23,223